1. Field of the Invention
The present invention relates generally to devices and methods for the non-destructive evaluation of the condition of tubes, pipes, cylindrical shells and the like. The present invention relates more specifically to a probe structure and method for conducting ultrasonic, magnetostrictive, and other similar wave propagated evaluations of tubes, pipes, cylindrical structures and the like from the interior of such structures with limited access.
2. Description of the Related Art
Many industrial structures, frames, conduits, flow columns and the like, are constructed in cylindrical configurations that are often difficult to access. Inspecting small diameter tubing and pipes for defects and the effects of corrosion is important but extremely difficult due to the geometrical constraints of the available working space. Efforts to inspect such tubes and pipes from the outside diameter (OD) is restricted because of the frequent use of supporting structures that are attached to the external surface of the pipes or tubes. Ideally, the easiest longitudinal access to such tubular pipe structures is from the inside since most frequently the interior walls are free from limiting support structures. Unfortunately, the aforementioned constraints of the typical cross-sectional geometries of tubing, pipes and the like, prohibit the introduction of the necessary probes and electronics into the internal diameter (ID) of the target tubing.
Once the interior diameter of a target tube is accessed, ultrasonic waves and magnetostrictive based mechanical waves can be used to inspect the tube wall for defects and/or wall thinning. The problem in most every instance is actually injecting the interrogating waves into the interior surface of the tube walls. In addition, the types of waves most suitable for inspection of the length of a target tube are those that propagate longitudinally through the walls in a uniform and symmetrical fashion. In other words, insertion of interrogating waves at a single point in the cylindrical wall of a tube would generally introduce conflicting wave patterns that complicate the detection and analysis of signal returns from anomalies. It is preferable to inject interrogating waves in uniform and symmetrical form so as to simplify the reception, interpretation, and analysis of a return signal.